1. Field of the Invention
This invention relates to an image forming apparatus using the electrophotographic art and to a process cartridge removably mountable with respect to this image forming apparatus. Here, the term "image forming apparatus" covers, for example, electrophotographic copying apparatuses, electrophotographic printers (such as LED printers and laser beam printers), electrophotographic facsimile apparatuses, etc.
2. Description of the Related Art
In an image forming apparatus using the electrophotographic image forming process, there has heretofore been adopted a process cartridge system in which an electrophotographic photosensitive member and process means acting on the electrophotographic photosensitive member are integrally made into a cartridge and this cartridge is made removably mountable in a body of an image forming apparatus.
According to this process cartridge system, the maintenance of the apparatus can be done by a user himself without resorting to a serviceman and, therefore, the operability of the apparatus is markedly improved. So, this process cartridge system is widely used in image forming apparatuses.
Now, a photosensitive member must be accurately rotated in an apparatus in which the accuracy of image formation is crucial like a color image forming apparatus using a plurality of colors of developers to form an image on a recording medium.
However, in a process cartridge according to the prior art, priority has been given to the ease of its mounting into the body of the image forming apparatus and, therefore, the accuracy of rotation of the photosensitive member has been somewhat sacrificed. That is, in order to facilitate the mounting of the process cartridge, in many process cartridges, there is only one power contact between the process cartridge and the body of the image forming apparatus. In many of them, only the photosensitive member directly receives a drive force from the body, and the rotatable members other than the photosensitive member in the process cartridge, for example, a feed blade, screw, etc. for feeding waste toner to a waste toner containing portion, have received a drive force through a gear provided on the flange of the photosensitive member. Consequently, the accuracy of rotation of the photosensitive member is reduced due to the pitch irregularity of this gear.